>>> Preparing source in /var/tmp/portage/kde-misc/wacomtablet-3.1.1-r1/work/wacomtablet-3.1.1 ... * Applying wacomtablet-3.1.1-xlib-optional.patch ... [ ok ] * Applying wacomtablet-3.1.1-gcc9.patch ... [ ok ] * Applying wacomtablet-3.1.1-correct-width-height-values.patch ... [ ok ] * Applying gcc9.patch ... 1 out of 1 hunk FAILED -- saving rejects to file src/common/libwacomwrapper.cpp.rej [ !! ] * ERROR: kde-misc/wacomtablet-3.1.1-r1::gentoo failed (prepare phase): * patch -p1 failed with /etc/portage/patches/kde-misc/wacomtablet-3.1.1/gcc9.patch
That's your own user patch failing.
Hmmm... That was set for /etc/portage/patches/kde-misc/wacomtablet-3.1.1/ and not for wacomtablet-3.1.1-r1 - is portage mishandling this?